Apparatus for cooling the bearings



Jan. 31, 1956 J M DONALD 2,733,001

I APPARATUS FOR COOLING THE BEARINGS OF FANS Filed Oct. 1, 1952 k 22 I I g'au raga.

United States Patent APPARATUS FOR COOLING THE BEARINGS 0F FANS John E. McDonald, Newton, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 1, 1952, Serial No. 312,572

1 Claim. (Cl. 230-211) This invention relates to fans, and relates more particularly to means for cooling the bearings of forced draft fans by air induced to flow through the bearings.

Open inlet forced draft fans used to supply air for combustion to the boilers of steam power plants, usually recirculate, at low plant loads, hot air through a hot air heater for maintaining its temperature above the dew point temperature of the flue gases which indirectly heat the air. The recirculated air not only is hot but is not clean so that air from the outlet of such a fan cannot be used satisfactorily for cooling its bearings.

Spin vanes of the type disclosed in the H. F. Hagen Patent No. 1,989,413, are often used for adjusting the volume of air handled by such a forced draft fan, and when adjusted near their closed postions so greatly reduce the volume of air handled by the fan that, even though operated at constant speed, the air drawn in throughan inlet of the fan is insufficient to cool a hearing located in the path of air entering the inlet.

This invention cools the bearings of such a fan by inducing air at atmospheric pressure through the bearings by the low pressure adjacent the inlet to the fan wheel. A bearing has a suction connection terminating adjacent an inlet of a fan wheel, and which extends, when the spin vanes approach closed position, through cut-outs in a pair of adjacent spin vanes where they overlap when closed. The hearing has an inlet connection for clean air at atmospheric pressure.

The difference in pressure causes clean air to move through the bearing for cooling the bearing surfaces.

An object of the invention is to cool a bearing of a fan by drawing air through the bearing into the fan.

Another object of the invention is to cool a bearing of an open inlet, forced draft fan having spin vanes in the inlet, by drawing air through the bearing into the .fan through a connection which extends between a pair of adjacent spin vanes.

The invention will now be described with reference to the drawings, of which:

Fig. 1 is a cross-sectional view of a portion of a centrifugal fan embodying this invention;

Fig. 2 is a fragmentary View looking into the inlet of the fan of Fig. 1, with the spin vanes partially closed; and

Fig. 3 is an enlarged view, partially in section of the bearing shown by Fig. 1.

The fan wheel is mounted on the rotary shaft 11, and has a curved side plate 12 which extends at its outer end, around the inner end 13 of the inlet sheet 14 of the fan.

The inner wall 15 of the fan is connected to the outer end of the inlet sheet 14, and is spaced from the outer wall 16 of the fan for providing a recirculated hot air passage 17 which discharges into the fan inlet passage 18 which is defined by the inlet sheet 14. The outer wall 16 has a circular opening 19 arranged centrally around the shaft 11, and which forms the primary air inlet of the fan.

The shaft 11 has therearound the toroidal shaped member 20in which the inner ends of the pivot rods 21 of the 2,733,001 Patented Jan. 371, 1956 spin vanes 22 are journalled, and which contains mechanism for rotating the rods 21, which mechanism is disclosed in. detail by the M. S. Leonard Patent No. 2,063,175. The outer ends of the pivot rods 21 are journalled in the inlet sheet 14.

The bearing v23 of the fan is supported on the pedestal 24 around an outer end of the shaft 11, and comprises an outer shell 25 spaced from, and forming an air passage 26 around the bearing surfaces which contact the shaft. The outer end of the shell 25 has an air inlet tube 27 extending therethrough into the passage 26 for admitting clean air thereinto. The shell also has the two air outlet tubes 31 extending therethrough into the passage 26, and which are connected at their upper ends into the horizontally extending tube 28, the outer end 29 of which is closed, and the open inner end 30 of which terminates adjacent the inner end 13 of the fan inlet passage 18.

The tube 28 extends between two adjacent spin vanes 22, the adjacent inner edges of which have semi-circular cut-outs as illustrated by Fig. 2 of the drawing, for receiving the tube 28 when the vanes overlap when partially closed.

The fan illustrated is a double inlet fan with only one wheel, one inlet, one set of spin vanes, and one bearing shown for simplifying the drawings and descriptions. It will be understood that the other bearing of the fan is similar to the one illustrated by Figs. 1 and 3 of the drawings, and is cooled in the same way.

In operation, since the inner end 30 of the tube 28 is adjacent the zone of lowest pressure produced by the fan wheel 10, and since the tube 27communicates with the atmosphere, the difference in pressure causes air to be drawn into the tube 27, through the passage 26 within the bearing, and through the tubes 31 and 28 into the fan. The clean cool air passing through the bearing passage 26 passes over the active bearing surfaces and effectively cools the latter.

With the spin vanes 22 in wide open position as illustrated by the dashed lines of Fig. 1, some of the primary air drawn into the fan will pass over the bearing shell 24 and will partially cool the bearing 23. However the air drawn at high velocity according to this invention in direct contact with the active bearing surfaces is made more efiective for cooling the latter.

Furthermore when the spin vanes are adjusted towards closed position as illustrated by Fig. 3, the volume of air entering the fan is greatly decreased, and the volume of air passing over the bearing 23 is greatly reduced. However the spinning of air at the downstream side of the spin vanes creates a low pressure, below atmospheric pressure, and cooling air is induced through the bearing. It will be understood that such fans are driven at constant speed, volume adjustment being provided by adjustment of the spin vanes, so that the fan bearings require cooling when the fan is operated to provide low air volumes.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact apparatus and arrangement of apparatus, since modifications thereof may be suggested by those skilled in the art, without departure from the essence of the invention.

What I claim as my invention, is:

A forced draft fan having a fan wheel on a rotary shaft, and having an axial inlet passage around the shaft,

air outlet and having its other end terminating adjacent said Wheel, said tube extending between a pair 6f said vanes, the adjacent edges oflthe vanes of said pair having cut-outs for clearing said tube when said vanes are adjusted to closed position. a 7

References Cited in'the "file of this patent UNITED STATES PATENTS 4 FOREIGN PATENTS Germany Sept. 9, 1922 Germany Dec. 30, 1930 

